To make chickpea flour batter, stir together the chickpea flour, turmeric, salt, and water in a bowl. Whisk together until blended completely making sure to eliminate all of the lumps.
Cover with plastic wrap and let the mixture rest at room temperature for at least 2 hours.
After 2 hours, add shredded pumpkin, finely chopped swiss chard (or kale), chopped scallions, minced garlic, 1 level teaspoon baking powder, and 1 tablespoon olive oil. Stir until all is well combined. Taste and adjust seasonings as needed.
Preheat oven to 200 °C. Line an 18 cm springform pan with baking paper and put it in the oven for approx. 5 minutes (it needs to be really hot when you add the batter).
After 5 minutes, coat the hot pan with 1 tablespoon olive oil and pour in the batter. Bake for approx. 35-38 minutes until the edges are golden and crispy. Cooking time depends on the thickness of the frittata, so adjust accordingly.
Cool in the pan, then slice into wedges and serve.